Fascinating report. What time of day was this and how long did you observe it for? Duration matters a lot with these things, a few seconds and you could explain away almost anything, but sustained observation over several minutes is much harder to dismiss.
I've spent decades looking into NDE accounts and one thing that keeps coming up is how often experiencers describe encountering craft or structured objects during the experience itself, which makes me wonder whether perception of these things operates on a different level than we normally assume.
Were there other witnesses nearby even if you haven't tracked them down yet? Lake Tahoe has a lot of foot traffic, someone else must have clocked it. Also interested in whether it made any sound at all or was completely silent because that seems to be a consistent feature across credible reports.